Absolutely. I don't know how much capability SW NPM has in terms of grouping alerts or rolling them up in some way, so I threw it out there anyway. Even on a site basis though, if you can't reach the WAN router for a site (e.g. you know the link has gone down), it would be really neat if you could tell NPM that (some list of monitored objects) all sit behind that single WAN router, and if the router's down, implicitly everything behind it will be too, and to generate one big alert rather than 101 little ones for the 100 things behind the router.
Once you go beyond that level, or you have multiple paths to a site, it gets much more complex - now you have to check if, say, BOTH WAN routers are down, and only then suppress alerts behind that failed 'edge'. Tricky, and hard to maintain manually over time.